This invention relates to bending of plastic tubes, particularly nylon tubes but not necessarily limited to the same, and particularly as applied to automotive applications, appliances and other commercial or industrial applications, but not necessarily limited to the same.
Throughout this specification, for convenience, the term “nylon” may be used in referring to the plastic tube material. However, except where the context dictates otherwise, the expression is intended to include other plastic tube materials, including for example resin, polyamide or nylon-based materials.
Various plastic/nylon tubes are used to convey liquids and vapors in many applications, including automotive applications. These tubes are semi-rigid with very stable properties under various conditions of heat and light, and are therefore suitable for conveying liquids, including fuels and fuel vapors.
In these applications, so that the tube can be properly routed, it usually needs to be formed to a specific contour, i.e. with various bend radii, bend angles, bend rotations, and distances between bends. This forming process requires a staged sequence of heating, bending and cooling.
Many methods of forming plastic/nylon tubes using this sequence of heating, bending and cooling are currently in use. They generally use dedicated forming tools to produce one contour consisting of multiple bends of varying radii, bend angle, bend rotation, and distance between bends. The tube is heated using hot air or other means in its straight form, transferred into a steel forming tool or series of tools to bend the tube to the desired contour, cooled in place using cold air or water or other means, and removed having achieved the desired contour. Due to the dedicated nature of these bending methods, the tooling is expensive and generally not easily reconfigurable for different contours. Contour changes are very common, and are expensive and time consuming. This is disproportionately costly, especially for producing tubes in relatively low quantity. The dedicated tools and machines also require a large manufacturing space.
In view of the preceding, there is a need for a readily reconfigurable method of bending plastic/nylon tubes which is effective and efficient, and for apparatus to carry out the same.
In addition to being readily reconfigurable, the method and apparatus ideally would have a reasonably small footprint, and a short cycle time for each bend.